1. Field of the Invention
One embodiment of the present invention relates to a current detection circuit.
2. Description of the Related Art
In recent years, a current detection circuit which detects the amount of current flowing between two elements or circuits is known.
For example, when electric power is supplied from a photoelectric conversion device to a circuit which is a load and has a specific function (also referred to as a function circuit), it is preferable that a maximum power point tracker is provided and adjusts electric power supplied to the function circuit to have a maximum value. At that time, the maximum power point tracker includes a current detection circuit, a voltage detection circuit, and an arithmetic circuit. Values of a current and a voltage, which are supplied from the photoelectric conversion device, are detected by the current detection circuit and the voltage detection circuit, and the maximum power point tracker adjusts electric power supplied to the function circuit to have a maximum value in accordance with the detection result, with the use of the arithmetic circuit.
In some cases, a current detection circuit is provided to prevent reduction in cycling characteristics or breakdown due to overcharging of a lithium ion battery, for example.
As an example, the current detection circuit includes a differential amplifier circuit (e.g., Patent Document 1). As a differential amplifier circuit of a conventional current detection circuit, a differential amplifier circuit including a field-effect transistor is used, for example. A differential amplifier circuit including a field-effect transistor is used for a current detection circuit, whereby a manufacturing process can be simple and manufacturing cost can be reduced in comparison with the case of using an amplifier circuit including a bipolar transistor, for example.